The relationship of Na ion, K ion-ATPase and sodium transport to the formation of bile, in particular the bile salt independent fraction of canalicular flow, will be examined. The effects of various bile acids on these membrane enzymes as well as their effects on the morphology of the canalicular membrane (as determined by scanning electron microscopy), will also be determined. Chlorpromazine, a drug known to decrease bile secretion, to inhibit Na ion, K ion-ATPase in brain, and to produce jaundice in man, will be examined for its effect on hepatic membrane ATPases and canalicular membrane structure. Preliminary studies will also assess microfilament function in the liver cell and their relationship to ATPase activities in plasma membrane fraction. BIBLIOGRAPHIC REFERENCES: Boyer, J.L. and Reno, D: Properties of (Na ion and K ion)-activated ATPase in rat liver plasma membranes enriched in bile canaliculi. Biochem. Biophys, Acta. 401:59-72, 1975. Layden, T.J., Schwarz, J., and Boyer, J.L: Scanning electron microscopy of the rat liver - Studies of the effect of sodium lithocholate and other models of cholestasis. Gastroenterology 69: 724-738, 1975.